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Coital positions and clitoral blood flow: A biomechanical and sonographic analysis (2022)
K. Lovi, A. Marashi
Summary
Objective. — To create biomechanical models of five common coital positions, and evaluate the degree of contact and forces against the clitoris. To evaluate clitoral blood flow before and after engaging in these positions.
Methods. — Biomechanical models were rendered of a male and female pelvis in the following coital positions: face-to-face/female above, sitting/face-to-face, face-to-face/male above (with and without pillow), and kneeling/rear entry. The thrusting force and gravitational force were estimated for the pelvis(es) providing the main forces. The areas of contact between the pelvises were identified and highlighted. Sonography of the clitoris was performed before and after a healthy volunteer couple engaged in each position, using a Philips LumifyTM ultrasound (Koninklijke Philips N.V., Amsterdam, Netherlands) with an L12-4 linear array transducer (4—12 MHz).
Results. — The biomechanical models for each position, with the exception of kneeling/rear entry, reveal a large amount of contact with the clitoris. Clitoral blood flow increased after engaging in each position except for kneeling/rear entry. Positions in which the gravitational force of the thrusting partner was in the same direction of (and thereby augmenting) the thrusting force resulted in intense clitoral blood flow (face-to-face/female above, and face-to-face/male above). Augmenting the face-to-face/male above position with a pillow generated a component of the male pelvic gravitational force in the direction of the clitoris; this resulted in more blood flow to all components of the cavernous body.
Conclusion. — From a biomechanical perspective, different coital positions vary in their potential to stimulate the clitoris. These positions lead to variable increases in clitoral blood flow, concordant with our biomechanical models.
Introduction
The purported benefits of various coital positions are described in numerous magazines, books, and public forums. However, there is little scientific research that evaluates the association between different coital positions and their ability to produce a female orgasm. A survey of Swedish women evaluated the tendency of various sexual techniques (but not positions) to cause climax. In this study, 51—57% of women achieved orgasm through penile penetration alone, and 50% through clitoral stimulation alone (Fugl-Meyer et al., 2006). Swieczkowski and Walker evaluated the ability of different coital positions to produce orgasm by administering a questionnaire with a 40-point Likert scale (ranging from 0/‘‘not at all’’ to 40/‘‘exclusively’’). The average ratings, in order of decreasing orgasm potential, were: face-to-face/male above (28), face-to-face/female above (26.36), manipulation of female genitals by partner (23.47), cunnilingus (17.94), face-to-face/side position (16.73), stimulation of breasts and other non-genital areas (11.69), sitting/face-to-face (10.78), prone/rear entry (8.23), kneeling/rear entry (5.85), sitting/rear entry (3.81), stimulation by vibrator (2.26), and anal intercourse (0.89) (Swieczkowski and Walker, 1978).
In 2018, Krejcová et al. investigated coital positions in a group of Czech volunteers. Participants were shown a series of black and white drawings of 13 sexual positions and were asked to estimate what percentage of the time they led to orgasm; 9 positions were coital: face to face/male above, prone/rear entry, standing/face-to-face, standing, face-to-face/female above, supine/female above, kneeling/rear entry, sitting/face-to-face, and standing/rear entry. The most common positions (over participants’ lifetimes, and within the past 5 years) were: face-to-face/male above (median 80% for females), face-to-face/female above (median 40% for females), and kneeling/rear entry (median 42% for women). The face-to-face/female above and sitting/face-to-face positions were most likely to result in orgasm, while the kneeling/rear entry position was least likely (Krejcová et al., 2020).
Krejcová et al. attribute the success of face-to-face positions to their ability to facilitate communication, both verbal and physical (Krejcová et al., 2020). Although these psychological factors are involved in orgasm (Meston et al., 2004; Brody, 2010; Brody and Costa, 2017; Adam et al., 2020), physical stimulation of the clitoris, which has been recognized as ‘‘possibly the most critical organ for female sexual health,’’ likely plays a dominant role (Mazloomdoost and Pauls, 2015). The female orgasm is hypothesized to be regulated by both autonomic and somatic nerves and involves a complex reflex arc. According to O’Connell et al. (O’Connell et al., 2005), this process probably involves:
• Receptors within the clitoris and vulva detecting stimulus (i.e. touch);
• somatic afferents of the pudendal nerve (dorsal clitoral and perineal branches);
• S2-4 spinal cord levels transmitting information to the brain;
• visceral efferents of the pelvic splanchnic nerves;
• parasympathetic stimulation of the clitoris resulting in dilation of the clitoral arteries;
• erectile tissue of the clitoris becomes engorged with blood (increased inflow and decreased outflow of blood);
• secretions from the Bartholin and/or Skene glands and urethra;
• sympathetic stimulation of the urovaginal plexus (through the hypogastric nerves and inferior hypogastric plexus);
• skeletal muscle contraction of the vagina, anus, and urethra (through the pudendal nerve).
From a biomechanical perspective, pelvic floor muscles are also crucial to orgasm, with stronger pelvic floor muscles associated with improved sexual function (Kanter et al., 2015; Kegel, 1952; Graber and Kline-Graber, 1979; Lowenstein et al., 2010; Martinez et al., 2014). Although other biomechanical factors (i.e. forces against the clitoris) likely play a major role in this process, the female orgasm has yet to be formally studied from this perspective. Researchers generally agree that there is a distinction between orgasms resulting from clitoral stimulation, or ‘‘clitoral orgasm’’ (CO), and those resulting from vaginal penetration without clitoral stimulation, or ‘‘vaginally activated orgasm’’ (VAO) (Jannini et al., 2012; Buisson and Jannini, 2013). A VAO is hypothesized to involve stimulation of the clitorourethrovaginal (CUV) complex (Jannini et al., 2012; Buisson and Jannini, 2013). Buisson and Jannini performed a sonographic study to evaluate clitoral blood flow after external and internal stimulation (Buisson and Jannini, 2013). Additional sonographic studies have evaluated the CUV complex (Buisson et al., 2008; Gravina et al., 2008; Foldes and Buisson, 2009; Battaglia et al., 2009; Battaglia et al., 2010a; Battaglia et al., 2010b). However, no sonographic studies have been performed to evaluate the efficacy of different coital positions.
*Our study was limited to creating biomechanical models for five coital positions and evaluating changes in clitoral blood flow in one female volunteer after engaging in these positions. Individual women might have different responses to stimulation from these positions. Additionally, different partners might exert varying degrees of thrusting forces, which would impact the predictions of the biomechanical models. Psychological factors also play a role in clitoral blood flow and orgasm and are not accounted for in this investigation (Meston et al., 2004; Brody, 2010; Brody and Costa, 2017). Since this is a pilot study, it is important that it be replicated with a larger number of subjects.
Conclusions
Our findings suggest that, from a biomechanical perspective, different coital positions vary in their potential to stimulate the clitoris. These positions lead to variable increases in clitoral blood flow, concordant with our biomechanical models. According to our results, face-to-face positions are more likely to lead to orgasm because they maximize clitoral stimulation and blood flow. In addition, positions in which the female partner has more control over the pressure exerted on the clitoris (i.e. female above) produce more uniform increases in clitoral blood flow. These results can help clinicians inform patients with sexual dysfunction. Difficulty achieving orgasm, the causes of which are multifactorial, is one component of sexual dysfunction. Clinicians can use these findings to counsel patients about which coital positions might help them achieve climax.
K. Lovi, A. Marashi
Summary
Objective. — To create biomechanical models of five common coital positions, and evaluate the degree of contact and forces against the clitoris. To evaluate clitoral blood flow before and after engaging in these positions.
Methods. — Biomechanical models were rendered of a male and female pelvis in the following coital positions: face-to-face/female above, sitting/face-to-face, face-to-face/male above (with and without pillow), and kneeling/rear entry. The thrusting force and gravitational force were estimated for the pelvis(es) providing the main forces. The areas of contact between the pelvises were identified and highlighted. Sonography of the clitoris was performed before and after a healthy volunteer couple engaged in each position, using a Philips LumifyTM ultrasound (Koninklijke Philips N.V., Amsterdam, Netherlands) with an L12-4 linear array transducer (4—12 MHz).
Results. — The biomechanical models for each position, with the exception of kneeling/rear entry, reveal a large amount of contact with the clitoris. Clitoral blood flow increased after engaging in each position except for kneeling/rear entry. Positions in which the gravitational force of the thrusting partner was in the same direction of (and thereby augmenting) the thrusting force resulted in intense clitoral blood flow (face-to-face/female above, and face-to-face/male above). Augmenting the face-to-face/male above position with a pillow generated a component of the male pelvic gravitational force in the direction of the clitoris; this resulted in more blood flow to all components of the cavernous body.
Conclusion. — From a biomechanical perspective, different coital positions vary in their potential to stimulate the clitoris. These positions lead to variable increases in clitoral blood flow, concordant with our biomechanical models.
Introduction
The purported benefits of various coital positions are described in numerous magazines, books, and public forums. However, there is little scientific research that evaluates the association between different coital positions and their ability to produce a female orgasm. A survey of Swedish women evaluated the tendency of various sexual techniques (but not positions) to cause climax. In this study, 51—57% of women achieved orgasm through penile penetration alone, and 50% through clitoral stimulation alone (Fugl-Meyer et al., 2006). Swieczkowski and Walker evaluated the ability of different coital positions to produce orgasm by administering a questionnaire with a 40-point Likert scale (ranging from 0/‘‘not at all’’ to 40/‘‘exclusively’’). The average ratings, in order of decreasing orgasm potential, were: face-to-face/male above (28), face-to-face/female above (26.36), manipulation of female genitals by partner (23.47), cunnilingus (17.94), face-to-face/side position (16.73), stimulation of breasts and other non-genital areas (11.69), sitting/face-to-face (10.78), prone/rear entry (8.23), kneeling/rear entry (5.85), sitting/rear entry (3.81), stimulation by vibrator (2.26), and anal intercourse (0.89) (Swieczkowski and Walker, 1978).
In 2018, Krejcová et al. investigated coital positions in a group of Czech volunteers. Participants were shown a series of black and white drawings of 13 sexual positions and were asked to estimate what percentage of the time they led to orgasm; 9 positions were coital: face to face/male above, prone/rear entry, standing/face-to-face, standing, face-to-face/female above, supine/female above, kneeling/rear entry, sitting/face-to-face, and standing/rear entry. The most common positions (over participants’ lifetimes, and within the past 5 years) were: face-to-face/male above (median 80% for females), face-to-face/female above (median 40% for females), and kneeling/rear entry (median 42% for women). The face-to-face/female above and sitting/face-to-face positions were most likely to result in orgasm, while the kneeling/rear entry position was least likely (Krejcová et al., 2020).
Krejcová et al. attribute the success of face-to-face positions to their ability to facilitate communication, both verbal and physical (Krejcová et al., 2020). Although these psychological factors are involved in orgasm (Meston et al., 2004; Brody, 2010; Brody and Costa, 2017; Adam et al., 2020), physical stimulation of the clitoris, which has been recognized as ‘‘possibly the most critical organ for female sexual health,’’ likely plays a dominant role (Mazloomdoost and Pauls, 2015). The female orgasm is hypothesized to be regulated by both autonomic and somatic nerves and involves a complex reflex arc. According to O’Connell et al. (O’Connell et al., 2005), this process probably involves:
• Receptors within the clitoris and vulva detecting stimulus (i.e. touch);
• somatic afferents of the pudendal nerve (dorsal clitoral and perineal branches);
• S2-4 spinal cord levels transmitting information to the brain;
• visceral efferents of the pelvic splanchnic nerves;
• parasympathetic stimulation of the clitoris resulting in dilation of the clitoral arteries;
• erectile tissue of the clitoris becomes engorged with blood (increased inflow and decreased outflow of blood);
• secretions from the Bartholin and/or Skene glands and urethra;
• sympathetic stimulation of the urovaginal plexus (through the hypogastric nerves and inferior hypogastric plexus);
• skeletal muscle contraction of the vagina, anus, and urethra (through the pudendal nerve).
From a biomechanical perspective, pelvic floor muscles are also crucial to orgasm, with stronger pelvic floor muscles associated with improved sexual function (Kanter et al., 2015; Kegel, 1952; Graber and Kline-Graber, 1979; Lowenstein et al., 2010; Martinez et al., 2014). Although other biomechanical factors (i.e. forces against the clitoris) likely play a major role in this process, the female orgasm has yet to be formally studied from this perspective. Researchers generally agree that there is a distinction between orgasms resulting from clitoral stimulation, or ‘‘clitoral orgasm’’ (CO), and those resulting from vaginal penetration without clitoral stimulation, or ‘‘vaginally activated orgasm’’ (VAO) (Jannini et al., 2012; Buisson and Jannini, 2013). A VAO is hypothesized to involve stimulation of the clitorourethrovaginal (CUV) complex (Jannini et al., 2012; Buisson and Jannini, 2013). Buisson and Jannini performed a sonographic study to evaluate clitoral blood flow after external and internal stimulation (Buisson and Jannini, 2013). Additional sonographic studies have evaluated the CUV complex (Buisson et al., 2008; Gravina et al., 2008; Foldes and Buisson, 2009; Battaglia et al., 2009; Battaglia et al., 2010a; Battaglia et al., 2010b). However, no sonographic studies have been performed to evaluate the efficacy of different coital positions.
*Our study was limited to creating biomechanical models for five coital positions and evaluating changes in clitoral blood flow in one female volunteer after engaging in these positions. Individual women might have different responses to stimulation from these positions. Additionally, different partners might exert varying degrees of thrusting forces, which would impact the predictions of the biomechanical models. Psychological factors also play a role in clitoral blood flow and orgasm and are not accounted for in this investigation (Meston et al., 2004; Brody, 2010; Brody and Costa, 2017). Since this is a pilot study, it is important that it be replicated with a larger number of subjects.
Conclusions
Our findings suggest that, from a biomechanical perspective, different coital positions vary in their potential to stimulate the clitoris. These positions lead to variable increases in clitoral blood flow, concordant with our biomechanical models. According to our results, face-to-face positions are more likely to lead to orgasm because they maximize clitoral stimulation and blood flow. In addition, positions in which the female partner has more control over the pressure exerted on the clitoris (i.e. female above) produce more uniform increases in clitoral blood flow. These results can help clinicians inform patients with sexual dysfunction. Difficulty achieving orgasm, the causes of which are multifactorial, is one component of sexual dysfunction. Clinicians can use these findings to counsel patients about which coital positions might help them achieve climax.
